Musnad Ahmad 943:4

Surayj ibn al-Nu‘man narrated to us, Hushaym narrated to us, Mujalid informed us, from al-Sha‘bi, al-Ash‘ath ibn Qays narrated to us, he said: I arrived to the Messenger of Allah, peace and blessings of Allah be upon him, with the delegation of Kindah. He said to me: "Do you have any children?" I said: A boy was born to me on my journey to you from the daughter of Jamad, and I wished that in his place the people were fed. He said: "Do not say that, for in them is a delight of the eyes and a reward if they are taken (in death). Furthermore, if you say that, they are indeed a cause of cowardice and a cause of grief; they are indeed a cause of cowardice and a cause of grief."